Soft conformal laparoscopic instrument

ABSTRACT

A soft robotic instrument that is capable of changing its form factor (e.g., expanding and contracting) during use to facilitate minimally invasive surgery. The instrument may be formed wholly or partly of an elastomeric, electrically insulating material for mitigating the risk of injuring tissue and for mitigating the risk of electrical arcing during electrosurgery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application based on U.S. applicationSer. No. 14/645,301, filed on Mar. 11, 2015, which claims the benefit ofpriority under 35 U.S.C. § 119(e) to U.S. Provisional Patent ApplicationNo. 61/950,954 by Carl Everett Vause, et al. titled “Soft ConformalLaparoscopic Instrument.” The entire disclosure of the foregoingapplication is incorporated herein by reference for all purposes.

FIELD OF THE DISCLOSURE

The disclosure relates generally to the field of medical devices andmore particularly to soft robotic instruments for performing medicalprocedures.

BACKGROUND OF THE DISCLOSURE

Laparoscopic surgery is a surgical technique in which operations in theabdomen are performed through small incisions (usually 0.5-1.5 cm).There are a number of advantages provided to a patient undergoinglaparoscopic surgery versus an open surgical procedure. These include amuch smaller incision, reduced pain and hemorrhaging, and shorterrecovery time.

Modem laparoscopic instruments, including robotically-assistedlaparoscopic instruments, typically include an elongated shaft thatterminates in a mechanical end effector for reaching into a patient'sbody and manipulating the patient's tissue in a desired manner. The endeffector may be a simple mono-polar electrode, a toothed grasper,scissors, or some other device or structure that is adapted to perform adesired function during a laparoscopic procedure. Laparoscopicinstruments are generally formed of rigid materials, such as metals andplastics, in order to facilitate articulation, grasping, cutting, andother movements and/or actions that may be necessary.

Conventional laparoscopic instruments are associated with a number ofshortcomings. For example, due to their rigidity, and since they aregenerally not conformal and are not capable of significantly alteringtheir shape during use, such instruments have outer dimensions thatdefine minimum and maximum dimensions of surgical access ports inpatients' through which they extend. This restricts the number of usefulprocedures and operating environments in which such instruments may beemployed.

A further shortcoming associated with conventional laparoscopicinstruments is that, since these instruments often include teeth,blades, jaws, serrations, or other such features that are formed of hardplastic and/or metal, there exists a significant risk of unintentionallyinjuring tissue while performing a laparoscopic procedure, such as mayresult from accidental and/or overly-forcible contact with tissue.

A further shortcoming associated with conventional laparoscopicinstruments is that, in embodiments of such instruments that havemetallic surfaces and that are used for performing electosurgery and/orare used in conjunction with other instruments that are used forelectrosurgery, instances of electrical arching have been known tooccur, sometimes resulting in injury to patients.

The above described challenges have heretofore been mitigated byheightened surgeon awareness, extensive training, and complete avoidanceof certain anatomical structures and pathologies that are known topresent challenges. This places a significant burden on surgeons andlimits the range of applications in which laparoscopic instruments maybe used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is perspective view illustrating a first exemplary embodiment ofa soft robotic instrument in accordance with the present disclosure.

FIG. 1b is a side view illustrating an exemplary embodiment ofpressurizeable fluid source in accordance with the present disclosure.

FIG. 1e is a cross sectional view illustrating a shaft cuff of the softrobotic instrument shown in FIG. 1 a.

FIG. 2a is perspective view illustrating a second exemplary embodimentof a soft robotic instrument in accordance with the present disclosurein a pressurized configuration.

FIG. 2b is perspective view illustrating the soft robotic instrumentshown in FIG. 2a in a depressurized configuration.

FIG. 3a is perspective view illustrating a third exemplary embodiment ofa soft robotic instrument in accordance with the present disclosure in apressurized configuration.

FIG. 3b is perspective view illustrating the soft robotic instrumentshown in FIG. 3a in a depressurized configuration.

FIG. 4 is perspective view illustrating a fourth exemplary embodiment ofa soft robotic instrument in accordance with the present disclosure.

FIG. Sa is perspective view illustrating a fifth exemplary embodiment ofa soft robotic instrument in accordance with the present disclosure inone of a pressurized or depressurized configuration.

FIG. Sb is perspective view illustrating the soft robotic instrumentshown in FIG. Sa in a depressurized or pressurized configuration,depending upon whether the configuration of FIG. Sa is pressurized ordepressurized, respectively.

SUMMARY OF THE INVENTION

“Soft robotic” actuators that are configured to perform new fundamentalmotions—such as bending, twisting, and straightening—are described. Softrobotic technologies are discussed in PCT International PublicationNumber WO2012/148472, which is incorporated herein by reference in itsentirety. The present invention includes the implementation of softrobotic technologies into specific configurations that are useful forminimally invasive surgical techniques, and minimally invasive surgicalmethods that employ such soft robotic configurations.

Certain embodiments of the present disclosure describe fabrication andoperation of pressurizable networks of channels or chambers (Pneu-Nets)embedded in elastomeric or extensible bodies. The pressurizable networkactuators can be programmed to change shape and mechanical propertiesusing an external stimulus, including pneumatic or hydraulic pressure.The soft robot structures utilize designs of embedded pneumatic orhydraulic networks of channels in elastomers that inflate like balloonsfor actuation or in folded extensible fabrics that can open up whenpressurized. A plurality of chambers embedded within an elastomer can beused as a series of repeating components. Stacking and connecting theserepeated components provide structures capable of complex motion. Inthis type of design, complex motion requires only a single pressuresource (although more than one source can be used, if desired). Theappropriate distribution, configuration, and size of the pressurizablenetworks, in combination with a sequence of actuation of specificnetwork elements, determine the resulting movement.

In one aspect, the present invention relates to a medical device thatincludes a soft robotic actuator (referred to, for brevity, as an“actuator”) comprising an elastomeric material and a plurality ofinterconnected fluid compartments. The actuator is moveable betweenfirst and second configurations characterized by different first andsecond internal pressures within the plurality of fluid compartments,respectively. The device also includes a fluid conduit sized and shapedto couple to a fluid source, which conduit is in fluid communicationwith at least one of the fluid compartments so as to transmit fluidpressure between the fluid source and the fluid compartment(s). Themedical device can optionally include one or more additional features.For instance, the actuator can include a strain limiting portion aboutwhich the actuator bends when moved between the first and secondconfigurations. Alternatively or additionally, the second configurationcan be characterized by a larger outer diameter than the firstconfiguration, and the outer diameter of the first configuration can beless than the inner diameter of a medical device (such as a dilator, anintroducer sheath, and a working channel of a laparoscope or endoscope)through which the medical device is inserted into a patient. When it ismoved from the first to the second configuration, the actuatoroptionally undergoes a motion such as bending, twisting, curling andstraightening. In some cases, the device includes a plurality ofactuators defining a grasping structure, in which case the graspingstructure may be open when the actuators are in a first configurationand closed when the actuators are in the second configuration, or viceversa. The grasping structure may also include a mesh, a membrane or apolymer sheet extending between the plurality of actuators, such thatthe grasping structure defines a cup. In some cases, the device includesfirst and second loop shaped actuators which define a substantiallyspherical space. To do this, the second actuator is attached to thefirst actuator but is oriented transversely to it. Additionally, thedevice optionally includes a user-activated mechanism for moving fluidbetween the fluid reservoir and the plurality of fluid chambers.

In another aspect, the present invention relates to a system fortreating a patient that includes a medical device comprising an actuatorand a fluid conduit substantially as described above, along with a fluidsource configured to couple to the fluid conduit and a user-activatedmechanism (also as described above) for moving fluid between the fluidsource and the plurality of fluid compartments, thereby changing theconfiguration of the actuator. The system preferably (though notnecessarily) includes a hollow shaft, in which case the actuator isslidably disposed within the hollow shaft. As discussed above, thesystem can also include a plurality of actuators defining a graspingstructure, in which case the grasping structure may be open when theactuators are in a first configuration and closed when the actuators arein the second configuration, or vice versa. The grasping structure mayalso include a mesh, a membrane or a polymer sheet extending between theplurality of actuators, such that the grasping structure defines a cup.Alternatively, the system includes first and second loop shapedactuators which define a substantially spherical space. As above, thisis accomplished by means of the attachment and transverse orientation ofthe second actuator relative to the first actuator. The method alsooptionally includes

In another aspect, the present invention relates to a method of treatinga patient which includes inserting at least part of a medical device orsystem comprising a soft robotic actuator and fluid source, as describedabove, into the body of a patient. The method can also include movingthe actuator from the first to the second configuration, which step mayentail contacting a body tissue and/or a medical instrument with theactuator. Alternatively or additionally, the step of moving the actuatorincludes one or more of pushing, pulling or grasping a body tissuewithout damaging the tissue. As is discussed in greater detail below,one advantage of the soft robotic actuators relative to currently usedrigid medical devices is that the soft robotic actuators may besignificantly less traumatic, facilitating the atraumatic orminimally-traumatic manipulation of delicate body tissues. In somecases, the insertion of the device into the body includes disposing adistal end of a hollow shaft (e.g. a catheter, cannula, dilator,laparoscope or endoscope working channel) within the body of the patientand advancing at least a portion of the medical device through thehollow shaft and into the body of the patient.

In still another aspect, a soft body robotic device includes a flexiblemolded body having a plurality of interconnected chambers disposedwithin the molded body. A portion of the molded body is comprised of anelastically extensible material and a portion of the molded body isstrain limiting relative to the elastically extensible material. Thethickness of the molded body is at least 1 mm. The soft body roboticdevice further includes a pressurizing inlet that is configured toreceive fluid for the plurality of interconnected chambers. The moldedbody in the soft body robotic device is configured to preferentiallyexpand when the plurality of interconnected chambers are pressurized bythe fluid, causing a bending motion around the strain limiting portionof the molded body.

And in another aspect, a soft body robotic device includes a flexiblemolded body comprising a plurality of interconnected pleated chambers.The flexible molded body includes a flexible material and is affixed toa strain limiting member in such a manner that the strain limitingmember forms a wall of the plurality of interconnected pleated chambers.The thickness of the molded body is at least 1 mm. The soft body roboticdevice further includes a pressurizing inlet that is configured toreceive fluid for the plurality of interconnected pleated chamber. Theplurality of interconnected pleated chambers are configured topreferentially unfold when the flexible molded body is pressurizedthrough the pressurizing inlet, causing bending motion around the strainlimiting member.

In yet another aspect, a soft body robotic device is capable ofextension. This soft robotic device includes a flexible molded bodyhaving a plurality of interconnected chambers disposed within the moldedbody. The soft robotic device also includes a sealing member in a facingrelationship with the flexible molded body, in which the flexible moldedbody and the sealing member together define a plurality of channels.Each channel is defined by upper, lower and side walls. The sealingmember is in a state of compression in its resting state. The softrobotic device additionally includes a pressurizing inlet in fluidcommunication with the plurality of channels. The plurality of channelsare positioned and arranged such that the soft body robotic deviceexpands to relieve the strain in the sealing member when the soft bodyrobotic device is pressurized through the inlet.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. The invention, however, may be embodied inmany different forms and should not be construed as being limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, like numbers refer to like elements throughout.

In accordance with the present disclosure, a soft robotic instrument isprovided that is capable of changing its form factor (e.g., expandingand contracting) during use to facilitate minimally invasive surgery.Although the present invention is described with specific reference tolaparoscopic surgical techniques, it is to be appreciated that thepresent invention may be equally applicable to other types of minimallyinvasive surgery. The instrument may be formed wholly or partly of anelastomeric, electrically insulating material for mitigating the risk ofinjuring tissue and for mitigating the risk of electrical arcing duringelectrosurgery.

Referring to FIG. 1a , a first embodiment of an instrument in accordancewith the present disclosure includes a grasping device 100 (hereinafter“the grasper 100”) that employs soft robotic actuators 102 in place ofmetal jaws that are typically employed by conventional laparoscopicgraspers. The actuators 102 may extend from an opening in an elongated,tubular shaft 103 that may be inserted into the body of a patient duringa laparoscopic procedure as further described below.

Each of the actuators 102 may be defined by a flexible body 104 havingone or more pressurizeable (e.g., inflatable) fluid channels and/orchambers 106 formed therein. A portion of the flexible body 104 may beformed of an elastomeric material and another portion of the flexiblebody 104 may be strain limiting relative to the elastomeric material.The elastomeric portions of the flexible body 104 may be caused to bendaround the strain limiting portions via pressurization anddepressurization of the fluid chambers 106, thereby allowing theactuators 102 to be controllably expanded, contracted, shaped, and/ormoved in a predefined manner.

The fluid chambers 106 may be connected to one or more pressurizeablefluid sources 105 (see FIG. 1b ), such as via fluid conduits (not shown)that extend through the shaft 103. The pressurizeable fluid source 105may be manually or automatically operated to pressurize and depressurizethe fluid chambers 106 in the actuators 102. Referring to FIG. 1b , anon-limiting example of the pressurizeable fluid source 105 may includea trigger-operated pump or piston 107 that drives an amount of workingfluid through a cylinder 109 that is coupled to the fluid conduits inthe shaft 103. Alternatively, the pressurizeable fluid source 105 may beembodied by any suitable pneumatic or hydraulic fluid pressurizationdevice, including, but not limited to, hand pumps, electric compressors,pressurized gas canisters, etc.

Each of the actuators 102 may be provided with a corresponding rigidwire 108 (e.g., Nitinol wire) embedded therein that may extend throughthe shaft 103. A portion of the wires 18 may protrude from a butt end ofthe shaft 103 and may be manually or automatically manipulated to deployand retract the actuators 102 relative to the tip of the shaft 103. Forexample, when the grasper 100 is used to perform a laparoscopicprocedure, the actuators 102 may be depressurized (e.g., deflated) and,having a reduced size relative to the pressurized configuration of theactuators 102 shown in FIG. 1a , may be fully retracted into the hollowinterior of the shaft 103. The shaft 103 may then be inserted into asurgical access port in a patient. Once the tip of the shaft 103 isappropriately positioned within the patient, the wires 108 may bemanipulated (e.g., pushed) to extend the depressurized actuators 102 outof the tip of the shaft 103 and into a suitable position within thepatient, such as surrounding a portion of tissue that is to be grasped.The pressurizeable fluid source 105 may then be actuated to pressurizethe actuators 102, causing the actuators 102 to expand, bend, and/ormove to grasp the desired tissue. The grasper 100 may then be used tomanipulate the grasped tissue in a desired manner.

When the grasper 100 is to be removed from the patient, the actuators102 may be depressurized and the wires 108 may be manipulated (e.g.,pulled) to retract the actuators 102 back into the shaft 103. The shaft103 may then be withdrawn from the surgical access port. It willtherefore be appreciated that the surgical access port need only be aslarge as is necessary to facilitate insertion and removal of the shaft103, and need not be so large as to accommodate the actuators 102 intheir expanded (i.e., pressurized), working configuration shown in FIG.1a . Moreover, since the actuators 102 are formed of a relatively soft,elastomeric material, the risk of unintentionally damaging tissue withinthe patient is mitigated relative to conventional laparoscopic grabbersthat are formed of rigid materials such as metal and plastic. Stillfurther, since the elastomeric material of the actuators 102 iselectrically insulating, the risk of electrical arcing duringelectrosurgery is mitigated relative to laparoscopic grabbers that havemetallic components and/or surfaces.

In addition to the rigid wires 108, it is contemplated that theactuators 102 may be provided with various other embedded, rigidcomponents to aid in the actuation, deployment, and/or retraction of theactuators 102. The actuators 102 may further be provided with rigidexterior features, including, but not limited to, teeth 110 and blades112, such as may be formed of metal or plastic, for aiding in thegrasping and/or cutting of tissue. Such rigid elements could be adaptedfor controllable actuation, such as through the introduction of variablefluid pressure, as well as via mechanical and/or electrical activation.It is further contemplated that the actuators 102 can be provided withembedded electrodes for performing mono-polar or bi-polarelectrosurgical techniques, such as electro-cautery. Still further, itis contemplated that the actuators 102 may be provided with embeddedtransducers for performing ultrasound or Doppler imaging. Still further,while the grasper 100 has been described and shown as having twoactuators 102, it is contemplated that the grasper 100 may be providedwith an additional number of similar actuators, such as may be suitableor advantageous for manipulating various types of tissue or organs.Still further, it is contemplated that the actuators 102 may be providedwith internal fluid conduits and outlet ports for conveying andexpelling liquid onto targeted tissue (e.g., to perform irrigation).Still further, it is contemplated that the actuators 102 may be providedwith internal compartments or channels for holding and controllablydeploying surgical instruments, such as biopsy needles or laser fibers.

Referring to FIGS. 1a and 1e , the grasper 100 may be provided with anelastic cuff 114 that may fit over the tip of the shaft 103. The cuff114 may be provided with a plurality of internal fluid chambers 116 a-cthat may each be connected to an independent, pressurizeable fluidsource (not shown) that may be similar to the pressurizeable fluidsource 105 described above. By selectively pressurizing anddepressurizing one or more of the compartments 116 a-c, the actuators102 may be controllably oriented (e.g., angled or otherwise displaced)relative to the shaft 103.

Referring to FIGS. 2a and 2b , an exemplary embodiment of a“multi-fingered” grasper 200 in accordance with en embodiment of thepresent disclosure is shown. The grasper 200 may be similar to thegrasper 100 described above, but may be provided with four actuators 202having internal fluid compartments that are connected to a commonpressurizeable fluid source that is similar to the pressurizeable fluidsource 105 described above. A lightweight meshing 204 may extend betweeneach adjacent pair of actuators 202 so that grasper 200 may, in itspressurized configuration shown in FIG. 2a , form a “cup” that definesan interior volume. The cup may be placed over a body of tissue that isto be removed or otherwise manipulated. Of course, it is contemplatedthat the actuators 202 may be configured to form various types ofenclosures other than a round cup, such as a tent or a box. Moreover, asdescribed above in relation to the grasper 100, the grasper 200 may beprovided with various rigid features, irrigation fluid conduits, and/orother embedded structures and devices.

Referring to FIG. 2b , the grasper 200 is shown in a depressurizedconfiguration. As can be seen, all of the actuators 202 are collapsedinto a single, longitudinally extending “finger” having a diameter thatis smaller than, or substantially equal to, the diameter of the shaft203 from which the actuators 202 extend. The meshing 204 may becollapsed within the actuators 202 in a folded/interleavedconfiguration. Thus, like the grasper 100, the grasper 200 may, in itsdepressurized configuration, be inserted into, and withdrawn from, asurgical access port in a patient that is only large enough toaccommodate the shaft 203.

In addition to the graspers 100 and 200 described above, it iscontemplated that a soft robotic laparoscopic instrument in accordancewith the present disclosure may be implemented using a variety of otherconfigurations for addressing various operating needs. For example,referring to FIGS. 3a and 3b , the instrument may be embodied by adisplacer 300 that may include a pair of longitudinally and laterallyoriented loop-shaped actuators 302 a, 302 b that are connected to oneanother in a transverse relationship to define a substantially sphericalvolume. The actuators 302 a, 302 b may have internal fluid compartmentsthat are connected to a common pressurizeable fluid source (not shown)that is similar to the pressurizeable fluid source 105 described above.A wire or tendon 304 may extend longitudinally from the shaft 303 andmay be connected to a distal terminus of the longitudinally-extendingactuator 302 a. After the actuators 302 a, 302 b of the displacer 300are pressurized as shown in FIG. 3a , the tendon 304 may be pulledlongitudinally into the shaft 303 (as indicated by the longitudinallyoriented arrow in FIG. 3a ) to radially expand the displacer 300 (asindicated by the laterally oriented arrows in FIG. 3a ). The pressurizeddisplacer 300 may thereafter be used to displace sensitive tissues(lung, liver, etc.) to provide convenient access to adjacent areas.

Referring to FIG. 3b , the displacer 300 is shown in a depressurizedconfiguration. As can be seen, the actuators 302 are collapsed into asingle, longitudinally extending “finger” having a diameter that issmaller than, or substantially equal to, the diameter of the shaft 303from which the actuators 302 extend. Thus, like the graspers 100 and 200described above, the displacer 300 may, in its depressurizedconfiguration, be inserted into, and withdrawn from, a surgical accessport in a patient that is only large enough to accommodate the shaft303.

Referring to FIG. 4, another soft robotic laparoscopic instrument inaccordance with the present disclosure may be embodied by a spade 400that may be used to displace or otherwise manipulate tissue within apatient. The spade 400 may include a single actuator 402 that may havean internal fluid compartment that is connected to a pressurizeablefluid source (not shown) that is similar to the pressurizeable fluidsource 105 described above. The spade 400 may thus be operably used inits pressurized configuration shown in FIG. 4, or may be depressurizedand collapsed for insertion into, and withdrawal from, a patient.

The spade 400 may be provided with a plurality of suction ports 404 thatmay be connected to a vacuum source (not shown). The spade 400 maythereby employ suction to firmly grasp tissue for secure manipulationthereof. This is particularly advantageous for grasping delicate,slippery tissue without causing damage thereto. The spade 400 mayadditionally be provided with a central aperture 406 for providingaccess to tissue by other surgical instruments while the tissue isgrasped by the spade 400. Although the use of suction ports 404 isdescribed with specific reference to spade 400, it should be appreciatedthat suction ports may be used with any embodiment of the presentinvention.

Referring to FIGS. Sa and Sb, another soft robotic laparoscopicinstrument in accordance with the present disclosure may be embodied bya finger 500 that may be used to grasp tissue within a patient. Thefinger 500 may include a single actuator 502 that may have an internalfluid compartment that is connected to a pressurizeable fluid source(not shown) that is similar to the pressurizeable fluid source 105described above. The finger 500 may be inserted into a patient in adepressurized, substantially straight or partially curled configurationas shown in FIG. Sa. After the finger 500 is positioned adjacent a pieceof tissue 504 that is to be grasped, the actuator 502 may bepressurized, causing the finger 500 to curl or wrap around the tissue504 one or more times as shown in FIG. Sb. The finger 500 may then beused to manipulate the tissue 504 in a desired manner. It should beappreciated that the finger 500 may be used for a variety of surgicalapplications, such as, for example clamping of blood vessels to providehemostasis, applying pressure to other bodily lumens to prevent orminimize flow of fluids or gases therethrough, or to facilitateanastomosis procedures.

In addition to the various embodiments, configurations, and featuresdescribed above, it is contemplated that a soft robotic laparoscopicinstrument in accordance with the present disclosure may be providedwith a modular configuration that would allow a plurality of differentinstruments (i.e., end effectors) to be interchangeably connected to asingle shaft and to corresponding pressurizeable fluid sources, rigidwires, vacuum sources, etc. It is further contemplated that such a softrobotic laparoscopic instrument could be used as a manual handinstrument. It is further contemplated that such a soft roboticlaparoscopic instrument could be attached to a rigid robotic arm. It isfurther contemplated that such a soft robotic laparoscopic instrumentcould be attached to a soft or hard “tentacle” of differing form factorsto enable a wristed motion and control of the instrument. It is furthercontemplated that such a soft robotic laparoscopic instrument could beimplemented in conjunction with other hard and/or soft robotic devices.It is further contemplated that such a soft robotic laparoscopicinstrument could be used in open surgery as well as in minimallyinvasive and laparoscopic surgery.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralelements or steps, unless such exclusion is explicitly recited.Furthermore, references to “one embodiment” of the present invention arenot intended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

While the present invention has been disclosed with reference to certainembodiments, numerous modifications, alterations and changes to thedescribed embodiments are possible without departing from the sphere andscope of the present invention, as defined in the appended claim(s).Accordingly, it is intended that the present invention not be limited tothe described embodiments, but that it has the full scope defined by thelanguage of the following claims, and equivalents thereof.

1. A medical device, comprising: an actuator, comprising an elastomericmaterial and a plurality of interconnected fluid compartments, whereinthe actuator is moveable between a first configuration characterized bya first internal pressure within the plurality of fluid compartments anda second configuration characterized by a second internal pressurewithin the plurality of fluid compartments, the second internal pressurebeing different than the first internal pressure; and a fluid conduitsized and shaped to couple to a fluid source, the fluid conduit in fluidcommunication with at least one of the fluid compartments and adapted totransmit fluid pressure between the fluid source and the at least onefluid compartment.